Propeller control



April 21, 1953 Filed Nov. 5, 1942 E. MARTIN PROPELLER CONTROL 4 Sheets-Sheet l INVENTOR ErZejZarZl% April 1953 E. MARTIN 2,635,700

PROPELLER CONTROL Filed Nov. 5, 1942 4 Sheets-Sheet 3 Erie Martain Patented Apr. 21, 1953 2,635,700 PROPELLER- CONTROL Eric Martin, West Hartford, Conn., assignor to United Aircraft Corporation, EastHartford, Conn., a corporation of Delaware Application November 5, 1942, Serial No. 464,620

24 Claims.

This. invention relates to hydro-controllable aeronautical propellers and an object of the inventionis the provision of devices which may be-selectively rendered effective for either automatic or manual pitch control.

Another object is the provision of a control incorporating means for continuously providing a visible indication of the pitch angle of the propeller.

A furtherobject of the invention resides in the provision of a more accurate and sensitive control means for a propeller.

- A still further object resides in the provision of an improved propeller control means which does not require a hydraulic connection between the speed responsive governor and the pitch changing mechanism of the propeller.

Other objects and advantages will be more particularly pointed out hereinafter or will become apparent as the description proceeds.

In the accompanying drawing, there is diagrammatically illustrated one embodiment of a control apparatus for the purpose of disclosing the invention. The drawing, however, is for the purpose of illustration only and is not to be taken as limiting or restricting the invention since it will be apparent to those skilled in the art that various changes in the illustrated embodiment may be resorted to without in any way exceeding the scope of the invention.

Fig. 1 is a diagrammatic view of the improved propeller pitch control means;

Fig. 1A is a schematic view of a portion of the device shown in Fig. 1 showing a dilierent propeller oil supply. I

Fig. 2 is a transverse sectional view at the front end of the propeller drive engine taken along the lines 2-2 of Fig. 2A with the control housing shown in full and showing the arrangement of the major elements of the control apparatus around the front or nose piece of the engine.

Fig. 2A is a longitudinal sectional view of the assembled propeller engine and control section.

Fig. 3 is a longitudinal sectional view on an enlarged scale of a speed responsive governor constituting one of the elements of the improved control apparatus.

The propeller, generally indicated at I0, has three blades, each provided in its shank with a vane motor of the type generally indicated at I2, and mounted in hub I4. Two of the blades are indicated at I6 and I8. Fluid under pressure is delivered by a, vmulti-cylinder pump, generally indicated at, 20, mounted on, and rotatable with, the propeller hub and having plungers 22 actuated by astationary cam 24 supported on a member such as the engine nosepiece 26 through which the l propeller shaft 28 extends. With this arrangement, as the propeller rotates relatively to cam 24 theplungers'will be actuated to withdraw fluid from the annular sump or reservoir 30 and deliver it under pressure to annular manifold 32. Sump 30 is connected through channels 34 and with two ports 38 and 40 in a cylindrical distributing valve 42 carried by the propeller hub. Manifold 32 is connected through channels 44 and 46 with a port 48 located at the mid-length of valve 42. The usual pressure relief valve 43 is provided between the inlet and the outlet of the pump. One side of vane motor I2 is connected through channel 50 with a port 52 in valve 42 adjacent port 40, and the opposite side of the motor is connected through a channel 54 with a port 56 adjacenttoport 33. Within valve 42 is a follow-up valve in the form of a sleeve '60 slidable in the casing and provided with ports which can register with the above-mentioned ports in the casing. Within follow-up sleeve 60 is a slidable pilot valve 62 having a pair of pistons 64 and 66. Piston 64 controls the connections within the sleeve between port 56 and ports 38 and 48, while piston 66 controls the connection between port 52 and ports 40 and 48.

Pilot valve 62 isv connected by its stem 68 to a flange 10 mounted on a hub 12 passing through stationary cam 24 and having on its other end a shifter ring 14. Elements I0, I2 and 14 form a unit constrained to rotate with shaft 28 by a feather key I6 which, however, permits longitudinal adjustment of the unit (and of pilot valve 62) by a servo-motor generally indicated at E8.

The movable outer portion of pitch-changing motor I 2 is provided with a cam which serves to move sleeve 60 longitudinally by means of a lever 82, pivoted at 84, attached to sleeve 60 at 86, and having a contact shoe 88 held against cam 80 by a spring 90.

. In Fig. 2A the ports 38 and 40 of Fig. 1 are represented by the open right-hand end of the sleeve 60 and a hole through the interior of plunger 62 and a hole I33through the side of the plunger. The connection between the sleeve member 60 and the propeller pitch changing mechanism is represented by gears I43, I45 and I41, rotatable spiral cam I49, stationary member I 5 I, slotted at I 53 and by pin I55 passing through sleeve 60, slot' I 53 and cam slots I51 of spiral cam- I49. For a more complete description, ref- 686,298, filed July26, 1946, by John E. Anderson 3 for Pitch Changing Mechanism as a continuation of application Serial No. 482,265, filed April 8, 1943.

If now servo-motor I8, acting through shaft 92, finger 94 and shifter ring I4, moves valve 62 to the left, port 56 will be connected with port 48 permitting fluid under pressure to flow through channel. 54 to the chambers of motor I2 connected therewith, and-port 52 will be connected with port 40 permitting fluid to drain from the opposite side of the motor through channels 50 and 36 to sump 30. As the motor rotates-under these conditions to change the propeller pitch, cam 80 and lever 82 will move sleeve160.to;followup the movement of pilot-valve -62,-and-w-hen the pitch has been changed by an amount'corresponding to the movement .01;- th fpi Qt WB lYe, the ports of sleeve valve 60 will be brought into registry with pistons 64 and 66 thereby blocking channels 50 and 54 and locking the pitch changingmotor against further movement. :If, because of leakage ;of fluid in zthemotopnrxvalve; the pitch tends to change, the follow-up valveglinmwill be moved to reopen imports-admitting sufficient fluid under pressure to restore the pitch to the angle corresponding to the position of ,pilot valve 62. If the servo-motor again moves pilot valve 62, motor I2 will again be operated to change the pitch to an angle corresponding to the :new position of the pilot valve,,sothat the pitch angle of the :propeller has at :all times-avalu'e-corre- .sponding to the position ofpilot valve'62zas determined byrservo-motor :18.

:Servo-motor "I8 comprises .a-cylin'der 96 containing a piston-68secured on shaft 92iand'movable both directions from .its center position, and -.a positioning cylinder I arranged in tandem withcylinder 96 and-containing a piston I02 also secured on shaft 92. The end-of-sha-ft 92 opposite piston I62 extends into a cylindrical casing .I 04 and bears againsta compressionspring I 06 which urges shaft :92 towards the .left.

As shown in Figs. 2 and 2A, the displacement mechanism schematically shown at T8 in Fig. 1 comprises rack teeth '9I cut into shaft 92 and meshing with teeth 93 out in a small portion of the circumference .of-sleevei95 forming a portion of slip joint I4. Sleeve 95 is supported insideof an oil guard '9'] which is secured to the control support 99 by any suitable means. Oi1--guard:91 has spiral teeth I0I cut in-a portion of its inner circumference and sleeve' 95 has mating spiral teeth I03 cut in a portion of its external circumference so that longitudinal movement of shaft 6-2 will cause rotation-ofsleeve SSand -th'e spiral teeth IOI, I03 will-cause longitudinal reciprocation of the sleeve and hence ofthe slip joint 14. Control support 99 is secured to the nose "of the engineby means of cap screws I05.

Agovernor, generallyindicated. at I 08, is driven by shaft iIIO through "gears II'2, II3,4'I and'49. Shaft IIO drives a booster pump I14 and a pair of governor flyballs II6 which act in an upward direction on'a sleeve Ils slidable in a fixed casing I having ports 'I 22and I24'therein registerable with 'spaced'ports provided in sleeve I I8. Upward movement of sleeve I I8by flyballs II6 is resisted by a speeder spring I26, theloading on which may be adjusted by manually or automatically con trollable means such as the movable :abutment I28 and pinion I30 :rotatable by a lever, or by pulley I32. As such governor adjusting devices are well known a detailed description thereof is not necessary for the purposes of the present disclosure. The intake ofpump III-is throughfiuid channels I34 and I36, reservoir I38, and the outlet of the pump passes through channel I40 containing the pressure relief valve I42 and through channel I44 to port I22, the overflow from the relief valve I42 being returned to the sump through a channel I46. A channel I48 leads from governor port I24 to a valve I50 containing a plunger I52- movable by solenoid; I54 from the normal position illustrated in the drawing to a position in which it closes channel I46 and con- .anects a channel I56 with a channel I58 for a purpose to be presently described. From valve 150 a channel I60 continues from channel I48 and connects with channel I62 which leads to a :valve I64 having a plunger valve I66 movable 'fromthe open position, shown in the drawing, to

.,,a,closed po si ti on.by the solenoid I68. From valve I64 a channel I10 leads to the left hand end of aservo-motor cylinder 96 to force piston 98 to the right against spring I06, or to vent fluid from {this endpf the cylinder topermit spring 1106 to move-piston 93 and shaft92 totheleft. W:he.. hcr fluid is supplied-to ,cylinder96, or ventedtherefrom, depends upon the positionof the-governor valve sleeve II 8 which in one position connects pressure line I44 with channel I48 and in a different position connects channel I48 with sump I38 through drain :I 6-2 The right hand ends of cylinders 96 and I00 are-connected by channel I34 with reservoir I38 and the left end-of cylinder I00 is connected through channel I'Ill with the closed end of a-cyl- :inder Hficontaining a :piston I18 from which projects a rod I60 pivotally connected :to the end ofalever I 82 fulcrumed at I84, and connected at its-opposite end to a pilot valve I86 slidable in valve sleeveI-I-B. Valve I86 has spaced pistons cooperating with the ports -in sleeve H8 in a manner such that the fluid connection between the governor operated valve and theservo-motor is increasingly restricted as the servo-motor .piston moves away from the position it assumes when ,the governor is in its onspeed position thereby gradually slowing ,down the movement of the servo-motor piston to avoid overshooting or ,hun-ting of the control apparatus.

An adjustable'bleed I88 is provided between cylinder I76 and reservoir I38 which permits -;spring I90 to return valve I86 to a centered position relative to the governor operated sleeve I 18. As -=the ;change in propeller pitch corrects the speed deviation of the propeller; and-engine, the

;governor returnssleeve I'I'8 toitsneutral or onspeed condition in which the sleeve 'blocksline I48 and holds shaft 92 of the servo-motor in adjusted position. After the governor-sleeve II 8 and the pilot valve plunger I86 have returned-to their neutral positions ,a new on-speed condition will have been established with the propeller blades at a new pitch angle requiredto maintain the speed of the engine and propeller at the speed for which the governor is set.

In addition to the above described governor controlled or constant-speed operation of the pro- .peller, means are provided for manually controlling the propeller to maintain the pitch at a selected pitch angle, or to feather, unfeather, or reverse the propeller, as may be desired.

The manual control includes a'multiple switch, generally indicated at I92, having a shaft I94 carrying a manually movable selectorvknob I96 cooperating with a dial I98 having indications .zaesmoo a plurality of contact armsas indicated at 200. 1202, and 204, and is electrically connected with one side 206 of a power circuit by a brush 208.

When knob. I96 is set for constant-speed control, as shown in the drawing, arms. 200, 202, and 204 are all on dead contact points and the control of the propeller pitch is accomplished "entirely by the governor in the manner described :above.

During such governor control, however, and at all othertimes during operation of the propeller, the propeller pitch angle is visually indicated by pointers 2I0 and 2I2 on a dial2I4.

These pointers are actuated by means such as i the Autosyn, schematically illustrated in the I drawing, including an electrical unit 2I6 having a generator rotor mechanically connected-"with "shaft 92 by the rack and pinion arrangement M8, and a second electrical unit 220 electrically are mounted to rotate independently of shaft 222.

-Discs 228 and 230 are-rotated by gears 232 and -234 mounted on a shaft 236 rotatably by a hand i knob 238. This shaft 236 also carries a gear 240 which engages a gear 242 concentric with shaft 222 and carrying a pointer 244.

When it is desired to manually control the pitch, knob I96 is moved to the manual control position. This moves contact arms 200, 202, and

204 bringing arm 200 into contact with the dead contact point 246, arm 202 into contact with point 248 and arm 204 into contact with point 250. 'Manualknob 238 will then be rotated until pointer 244 is broughtto the position on dial 2 I4 indicating the desired pitch angle and will simultaneously rotate discs 228 and 230 to bring the contact "area 252 of disc 228 and contact area 254 of disc 230 to a particular angular position relative to dial 2 I4.

. Contact of arm 202 with point 248 will energize solenoid I54 moving valve plunger I52 to a position to intercept the governor line I48 and connect line I56 with line I58 thus putting the governor out of operation. Fluid under pressure may now be supplied to cylinder 96 of servo-motor 18 through line 256, valve 258, lines I56, I58, I60, and I62, valve I64 and line I10. Solenoid 260 controlling plunger 262 of valve 258 is controlled -by contact of arm 226 with the contact area 254 of disc 230.. This contact area overlies approximately one-half the circumference. of. the. disc .and is connected through brush 264, button 266 and conduit 268 with solenoid 260. Current is supplied toarm 226,through a brush 210 bearing on shaft 222 and, connected through switch points 250 and arm 204 with shaft I94 which is supplied with current throughbrush 208 from .circuit206. When arm 226 is out of contact with contact area 2'54 solenoid 260 is de-energized and .valve plunger 262 occupies the position shown in the drawing with fluid passing from the line 256 into cylinder 96 of the hydraulic motor. When .arm 226 is on contact area 254 solenoid 260 will .be energized and plunger 262 will occupy a position in which it intersects line 256 thereby cutting off the supply of fluid to the servo-motor and at the same timeconnecting lines I62 and I60 with a line 212 which is connected through the right of piston I02 with line I34 leading to ,reservoir I38, thus allowingfiuid to drain out of .cylinder 96 of the servo-motor and the piston 98 .t gpemo edbys ingI06... I

Assuming that pointer 244 has been manually set at the desired pitch angle and that this angle does not coincide with the existing pitch angle of the propeller, the servo-motor will be operated either by the admission of fluid under pressure thereto or by spring I06, depending upon whether arm 226 is in or out ofcontact with area 254. This operation of the servo-motor will operate the Autosyn unit to rotate shaft 222. and arms 224 and 226, the direction of rotation being controlled by whether the arm' 226 is in or out of contaotwith area 254. This rotation will continue. until arm 224 comes in contact with the shortcontact area 252 on disc 228. Engagement of arm 224 with area 252 will energize solenoid II68 of valve I64, moving plunger I66 to a valveclosing position and thereby cutting off line I10 .to prevent fluid from either entering orleaving the left hand end of the servo-motor cylinder 96.

The rotational position of shaft 222 at which arm 224 contacts area 252 coincides with the position at which pointers 2I0 .'and,2l2 are brought by the Autosyn into coincidence with the pitch angle selecting pointer 244. The closing of valve I 64 tends to lock the servo-motor in the position corresponding to theselected pitch angle. However, if there is any leakage in the servo-motor which permits piston 98 to move, arm 224 will be moved by the Autosyn out of contact with the contact area 252 thus opening valve I64 and causing additional fluid tobe admitted to the servo-motor to replenish that lost by leakage and thus the propeller will be automatically maintained at the pitch angle manually selected.

When it is desired to feather the propeller the manual selector knob I96 is moved to the indi cated feathering position bringing arm 200 into contact with point 214, arm202 into contact with point 216 and arm 204 into contact with the dead point 218. Movement of arm 204 to dead point 218, out of contact with button 250, breaks the circuit through arms 224 and 226 and throws the manual selecting mechanism out of operation. Contact of arm 202 with point 216 energizes solenoid I54 and maintains valve I50 in position to keep the governor out of operation, with the fluid connection from pump I I4 through line 256 open to valve I64. Since solenoid I68 of valve I64 is connected to the contact areas of discs 228 and 230 the breaking of this circuit will maintain solenoid I68 de-energized and valve I64 open so there is a continuous supply of fluid under pressure to the left end of cylinder 96. Contact of arm 200 with point 214 energizes solenoid 200 and retractsthe limit stop detent 282 from its illustrated position, in which it cooperates with spaced limit stops 2'84 and 286 to positively limit the range of pitch angles by limiting the possible movement of shaft 92 of servo-motor 18. With detent 282 out of the way the servo-motor can move to its limiting right hand positionthereby moving pilot 62 of valve 42 to its limitin high pitch position which will cause the pitch changing motors to feather the blades.

. When it is desired to return the propeller from feathered condition, knob I96 can be moved either to the manual control position, and a pitch'angle within the operating range selected, or knob I96 may be returned to the constant-speed position, permitting the governor to again take over the control of the propeller pitch. Such movement of knob I96 will release limit stop detent 282 and will return the control mechanism to the selected one of the twomodes of operation just mentioned. However, as the propellerdoes'not rotate when feathe'red, a source of fluid :un'der :pr'essure, or other means described below, is required to return the propeller from its Jfeath'ered conditionato a -pitch angle-iat which rotation is resumed with consequent resumption of operation-of the'pumps 20- and I114.

-When it. is desired to reverse the propeller the l2 to rotate the blades to a low'pitch position past the-low pitch limitstop 286, therebyreversing the pitch.

According to one methodthe unieathering operation mentioned above may be accomplished by connecting the'pitch changing'mechanism .to a high pressure -hy'draulicsystem carried by the airplane for operating'suchinstrumentalities as the landing gear, high lift'flanetc.

According to another method, operation of pump 29-may be resumed, with the propeller stopped, by providing a manually controllable electric motor 326 for driving the pump as shown in Fig. 1A. Such an arrangement is particularly illustra'tedand described in United States Application Serial No. 77,644, filed February 21, 1949, as a continuation of "application Serial No. 664,640, filed April 24, 1946, which is a continuationof application Serial No. 422,252, filed'December 9, 194l,by Donald W. Perin and Nelson.

R; Richmond for Propeller Control Mechanism. The unfeathering action in this structure is obtained by closing the switch '324 to energize the auxiliary pump driving electric motor 326. This motor, through its gear connections 328 and 330 will rotate the pump'cam member'24 which will operate the main pump 2!] to supply fluid under pressure to the distributing valve 42 and through this'valve to the pitch changing motor 12. By a suificient interval of operation of the motor 326 the propeller can be brought to its unfeathered condition withoutinitial rotation of the engine or "the :propeller. It is to be noted that the ear connection including the gears '32 8 'and330 which is actually an irreversible worm 'gear drive including an additional idler gear 335, as particularly illustrated in Fig. 2, is utilized'to prevent rotation of cam member 332 when the engine and propeller are operatingand the motor 326 is deenergized- As shown in Fig. 2, rotation of cam member'i i is also 'prev'ented by cam teeth 333 projecting from cammembenz i beyond gear 331) and contacting pivoted dog.339.

According to the method diagrammatically illustrated in the drawing, one or more pressure fluid accumulators, as indicatedat 292, are connected between pump 20 and the pitch changing mechanism and arranged to be filled with fluid under pressure from the pump'and to maintain this fluid under pressure. When the propeller is feathered the pressure fluid is trapped in the accumulators and retained therein until -it' is desired to unfeather the propeller. 'When'Ithe selector :knob ISG-ismoved-away from the feathering position this tfiuid is :released from :the

m'echanism in a manner to start the propeller blades :out'of theirfeathering'position. soon as the unfeathering operation has been thus started the propeller will begin to rotate and drive pump '29, so the operation may :be completed :by fluid from thatpump.

While a suitable mechanical embodiment for the 'purposeof disclosing the invention has=been her'einabove described and illustrated in the accompanying drawing, it is to be understood that the invention-is not limited to the particular embodiment so illustrated and describedbut: that such 'changesin the size',:shape, and arrangement .ofthe variousqparts may be resorted:to;-as.come withinthe. scope of the sub-joined claims.

Having now described the invention isothat others skilled in the art may clearly understand the same, :what it is'desired to secure 'by Letters Patentis .as follows:

1. A control for a hydraulically-actuatedvariable-pitch propeller providing four modes :of propeller operationwincluding, constantespeed operation, operation. :at manually "selected pitch angles, reverse operation and feathering operation, comprising automatically operating speed responsive means for adjusting the propeller pitch, "a valve actuated by saidspeed responsive means and controlling the flow of fiuid to and from the hydraulically actuated pitch changing mechanism of said propeller'when said propeller is operating insaid constant speed mode, and manually'operable means for actuating said valve and regulating the propeller pitch when the propeller is'operating in any of the other of said modes of operation including-means for locking said valve'during the manually controlled mode.

2. A control for a variable pitch propeller having blades and'a propeller'hub, comprisingpitch changing-means in the propeller hub, said means including a valve in'said hub, said valve having a follow-up connection with said blades to give said blades a definite anddifferentposition for each valve position, speed responsive means,

including a governor connected with a servomotor and operatively associated with said pitch changing means, for adjusting said "follow-up valve to adjust the pitch to maintain thepropeller speed at a selected value, manually operable means for disconnecting said governor froms'a'id servo-motor and said pitch changing means and manually controlling said servo-motor and'maintaining the propeller pitch'at amanually selected pitch angle.

3. A control fora'variable'pitchpropeller having'blades and a propeller hub, comprising, pitch changing means in the propeller hub, said'means including a valvein'said hub, said valve having a follow-up connection with said blades to give said blades a-definite and different position for each valvezposition, speedresponsive means, including agovernor connected with a servo-motor and operatively associated with said'pitchchanging means, for adjusting said follow-up valve to .select the pitch to maintain the propeller speed at aselected .value, manually operable means for disconnecting said governor from said servomotor andsaid pitch changing means and manually'controlling said servo-motor and maintaining the propeller pitch at a manually selected pitch angle, means operatively connected with said' valve for indicating the propeller pitch.

4. In a control providing various modes of-operation for a hydroecontrollable propeller including constant speed operation and feathering, a

propeller including pitch changing mechanisms, a follow-up valve carried by, said propeller for controlling the application of hydraulic fluid to the pitch changing mechanism of said propeller in all of its operative modes, said valve having two parts, one part being operatively connected with the propeller and another part controlled by control mechanism, said control mechanism including a servo-motor operatively connected with said other part of said follow-up valve for operating said valve, and speed responsive means. and, manually operable means operatively connected with said servo-motor for selectively operating said servo-motor. ,15. In a control for a hydraulically actuated variable pitch propeller providing several modes of -propeller operation including constant speed operation, operation at manually selected pitch angles, reverse operation and featheringloperation; automatically operating speed responsive m ans for adjusting the pr p l rr ch, a valve means actuated by said speed responsive means and controlling the flow of fluid to and frompthe hydraulically actuated pitch changing mechanism of said propeller when said propeller is operating in said constant speed mode, means for limiting the extent of pitch change possible under speed responsive control, manually operable means for actuating said valve means and regulating the propeller pitch when the propeller is operating in any of the other of, said modes of operation, including means for disabling said limiting means, v

Vfiu-A feathering variable pitch propeller having blades, comprising in-combination a motor for changing the pitch of the propeller blades,: a pump, carried by said propeller and operated by rotation of said propeller. for supplying fluid under pressure, a fluid line connecting said pump with said-motor, a two-part follow-rupvalve carried by said propeller and located in the line between said pump and said motor for controlling thBFfiOW of fluid to said motor, and having one partioperatively connected'with the blades'of said propeller'and another part connected with means movableqwith respect to said propeller, a servo-v motor mounted on a fixed support and'operatively connected with said means for moving said otherpartoftsaid valve; a governor controlling the operation' of saidservo-motor and manually actuated means for disconnecting said governor from said 'servo motor and manually controlling said servo-motor, I

1751A feathering variable pitch propeller having;blades,' comprising in combination a motor forfchanging'the pitch of the propeller blades,

a pump carried by said propeller and operated by? rotation of said propeller for supplying fluid under pressure, a'fluid line connecting said pump with said motor, a two-part follow-up valve carried by said propeller and located in the line between' 'said pump and said motor for controlling controlling the operation of said servo-motor and mandally actuated means for disconnecting said governor from said servo-motor and a manually controlling saidjser o'motor.

8. A feathering variable pitch propeller having blades, comprising in combination a motor for changing the pitch of the propeller blades, a self-contained fluid system carried by said propeller comprising, a chamber in said propeller for storing fluid, a pump connected with said chamber and carried bysaid propeller and operated by rotation of said propeller for placing fluid under pressure, a fluid line connecting said pump and said motor and a two-part follow-up valve carried by said propeller and located in the line between said pump and said motor for controlling the flow of fluid to said motor, said valve having one part operatively connected with the blades of said propeller and another part connected with means movable with respect to said propeller, means for moving said movable means and said other part of said valve for controllingthe pitch of said propeller and means for supplying said motor with fluid under pressure from said fluid system when the propeller is not rotating.

9. A feathering variable pitch propeller having blades, comprising in combination a motor for changing the pitch of the propeller blades, a self-contained fluid system carried by said propeller comprising, a chamber in said propeller for storing fluid, a pump connected with said chamber and carried by said propeller and op-- erated by rotation of said propeller for placing fluid under pressure, a fluid line connecting said pump and said motor and a two-part follow-up valve carried by said propeller and located-in the line between said pump and said motor'for con-- trolling the flow of fluid to said motor, said valve hav ng one part operatively connected-with the blades of said propeller and anothed 'part con-- 10. In combination, with a. controllable-pitch"- propeller having a hydraulically operated pitch changing motor, a control comprising, avalve in said propeller controlling the application ofhydraulicfluid to and the venting of hydraulic fluid from said motor, a cut-off element for said valve movable in accordance with all propeller pitch changes, a servo-motor for actuating said valve havin an element movable in both direct1ons, a speed responsive governor controlling said servo-motor and having a normal onspeed position, and means movable by said servonotor operative to temporarily reset said governorand slow down the operation of said servo-motor as the movable element thereof moves in either direction.

11. control for a controllable-pitch propeller having a hydraulically operated pitch changing motor comprising, a valve controlling the application of hydraulichfluid to and the venting of hydraulic fluid from said motor, a cut-ofl element for said valve movable in accordance with propeller pitch changes, a servo-motor mechanically connected with said valve for actuatmg the valve and having an element movable in both dlrections, a source of hydraulic fluid under pressure for operating said servo-motor, a governor operated valve having a, normal onspeedposition and located between said source and said servo-motor, and an element associateda'e'ssgzoo with said governor I actuated I valve and moved by movement ofsaidservo-motor to temporarily reset" said overnor and restrict the'fiuid connectionbetween said governor operatedvalve and said servo-motor as the movable element of said servo-motor moves.

.12. In combination" with a hydro-controllable propeller, 'a propeller-carried hydraulicsystem including a hydraulic pitch changing motor, a pump operated by rotation of said propeller for supplying hydraulic fluid #to said motor, and pump operating 'means including a normally stationary element, a' separate hydraulic system including a speed regulating governor and a servo-moton means operatively connecting said two hydraulic systems-whereby said system ineluding said speed regulating governor controls said system including said pitch changing motor, and an electric motor for said-element and operating-said pump independently of the -rotation or said propeller.

13. A control for a variable-pitch propeller having a" propeller hub, comprising, hydraulic pitch changing means in'the propeller hub, speed responsive means, including a governor connectedwith aservo-motor and operably associated with-said pitch changingmeans for adjusting the pitch changing means to adjust the propeller pitch to maintain-the propeller-speed at a selected value, manually operable means for disconnecting said-governor from said pitch changing means :*and manually controlling said pitch changing means and including means for maintainingthe propeller pitch-at any of a plurality of 'manually selected intermediatepitch angles.

14.: In combination with l a hydro-controllable propeller Ihaving a propeller-carried hydraulic system, including a hydraulic pitch changing motor and a pump, pump operating means comprising two relativelymovable elements; means for 'driving'one element with'respect to the other element by rotation of sa'idpropeller to con tinuously actuate said pump by-rotation of said cluding s'aid" speed regulating governor controls. saidsystem including-said pitch ch-angingmotor,

and an electric motor operatively connected with said other element for moving said otherelem'ent with respect to said one element and-operating said pump-independently of" the rotation of said" propeller.

15; 'Incombination with a' hydro-"controllable propeller having a propeller-married hydraulic system, including a hydraulic'pitch changing motor "and a pump, pump'operating means comprising means rotatable with the propeller, normally stationary means :operatively' associated with-*said-rotatable means and 'means for holding'said normally stationarfnreans stationary in pump operating'position at all times during propeller rotation for "continuously operating said pump by rotation of said propeller to maintain'a continuously energized source of hydraulic oper ating'fluid for said motor, a separate Ihydraulicsystem including a speed regulating governor and a servo-motor, means operatively connecting said two hydraulic systems whereby said system including said speed regulatin governor-controls said system including said pitch changingmotor.

16. -In combination with a hydro-controllable propeller having a pro'peller-carried hydraulic system, including a hydraulic pitch changing motor and a pumppmeans for continuously operating said pump by rotation of said propeller, and means for operating said pump 'indep'endently of the rotation of said propeller for supplying hydraulic operating fluid forsaid motor, a separate hydraulic system including a speed regulating governor and a servo-motorfmeam operably connecting said'two hydraulic systems whereby said system including said speed'regulating governor controls said system in'cluding said pitch changing motor. U

'1'75'In combination with a hydro-controllable propeller comprising, a propeller-carried hydrau-' lic system including a hydraulic pitchchanging motor and a pump, means actuated by rotation of 1 said propeller continuously actuating *said pump-and supplying hydraulic operating fluid for said motor, and means connecting said pump andsaid pitch changing motor including means for controlling the flow of operating fluid between said continuously actuated pump and said motor, a separate hydraulic system including a -speed regulating governor and a servo-motor, means operatively connecting said two hydraulic systems including means connecting-said servomotor and said operating fluid controlling means whereby-said system including said speed regu lating governor controls: said system including andpitch changing motor.

18. A feathering variable-pitchpropellerhavingablades, comprising, in combination a selfcontained'fluid system carried by said propeller comprising, a chamber in said propeller'for storing fluid, a pump 'connected with saidchamber, carried by said propeller and operated byrotation of said propeller for placing fluid under pressure, a motor for changing the pitch of salid blades, a fluid line connectingsaid pump and said motor, and a valve carried by saidpropeller and located in said-line between said pum .and said motor'for controlling the flow'offluid to said motor, valve .operating'mechanism including a two-part follow-up device having one'partoperatively connected with said blades,a separate hydraulic system for controlling :saidtpropell'ercarried fluid system including means'forcontrolling the position of said valve through theiother part of said follow-up device.

19. In combination with a hydro-controllable propeller, a propeller-carried hydraulic. system including a hydraulic pitch-changing motor. and

g a. pump for supplying a hydraulic fluid .to-said motor, means for operating said pump .by rotation of said propeller and means for operating said pump independently of the rotation of said propeller, a separate hydraulic'system including raspeed regulating governor and a servo-motor,-

valve, means operatively connecting said two hydraulicsystems including means operatively connecting said governorand said valve meansfor controlling said speed governor and a manual controlindependent ofv said. governor for-controlling said separate hydraulic system. J

21. In combination with a hydro-controllable propeller, a propeller-carried hydraulic system for changing the propeller pitch including a propeller-carried source of hydraulic pressure and a control Valve having a follow-up connection with the blades of said propeller, a separate hydraulic system having a separate source of hydraulic pressure remote from said propeller for controlling said propeller-carried hydraulic system, means operatively connecting said separate hydraulic system and said valve and means remote from said propeller for controlling said hydraulic system remote from said propeller.

22. A propeller control comprising a propellercarried hydraulic system including a pitch changing motor and a control valve therefor, a hydraulic system separate from said propellercarried hydraulic system comprising a servomotor and a control therefor, including a speed governor and a separate manual control for manually adjusting the position of said servo-motor, and means operatively connecting said servomotor with said pitch changing motor control valve.

23. A propeller control comprising a propellercarried hydraulic system including a pitch changing motor and a control valve therefor having a follow-up connection with the blades of said propeller, a separate hydraulic system comprising a servo-motor and a control therefor, including a speed governor, having a speed selecting control, for automatically adjusting the position of said servo-motor, and separate means for disconnecting said governor from said servomotor and manually adjusting the position of said servo-motor and means operatively connecting said servo-motor and said control valve so that each position of said servo-motor has a corresponding blade pitch position.

24. A propeller control comprising a propellercarried hydraulic system including a pitch changing motor and a control valve therefor having a follow-up connection with the blades A Number responding blade pitch position.

ERLE MARTIN.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Re. 20,283 Caldwell Mar. 9, 1937 1,987,651 Wiegand Jan. 15, 1935 2,145,859 Caldwell Feb. 7, 1939 2,163,663 Caldwell June 27, 1939 2,243,095 Hammond et al. l May 27, 1941 2,244,770 Englesson June 10, 1941 2,257,126 Rindfleisch Sept. 30, 1941 2,258,094 Keller Oct. 7, 1941 2,276,347 Ruths et al. Mar. 17, 1942 2,280,654 Mader Apr. 21, 1942 2,280,713 Martin et al. Apr. 21, 1942 2,296,288 Martin et a1 Sept 22, 1942 2,307,102 Blanchard et al. Jan. 5, 1943 2,307,849 Mullen Jan. 12, 1943 2,320,195 Rindfieisch May 25, 1943 2,361,954 Martin Nov. 7, 1944 2,391,699 Haines et al. Dec. 25, 1945 2,402,065 Martin June 11, 1946 2,403,532 Hoover July 9, 1946 2,404,290 Hoover July 16, 1946 2,422,966 Hoover June 24, 1947 FOREIGN PATENTS Number Country Date Italy Apr. 4, 1940 

